docs: adopt hybrid Codex Claude workflow

[PNHD]

Summary

• establish docs/AI_WORKFLOW.md as the canonical Hybrid Codex + Claude Code
  workflow for Focelle;
• add concise agent-specific AGENTS.md and CLAUDE.md;
• update project status and operational handoff to record the current
  FCL-M2 Batch A physical failure and recovery-audit gate;
• distinguish ChatGPT PM / Technical Lead responsibilities from the Human
  Product Owner / Operator;
• enforce one-writer worktrees, immutable review boundaries, risk-based
  Claude review, evidence levels and non-destructive Git rules.

Scope

Documentation and agent governance only.

Changed paths:

• AGENTS.md
• CLAUDE.md
• docs/AI_WORKFLOW.md
• docs/project-status.md
• .ai/SESSION.md

No product code, tests, project files, build configuration, CI configuration
or runtime behavior changed.

Evidence

• Base:
  82c94c09a70a8533dc44bc2655e97d9c59b4b354
• Head:
  07f2a553a45b9234757731596efdd32933736b41
• Local PM handoff review: PASS
• git diff --check: PASS
• Workflow worktree clean before publication

Current product state recorded

• FCL-M2 Batch A CI is green at its separate product SHA.
• Physical validation on iPhone 17e failed.
• Root cause is not yet established.
• PR FCL-M2 Batch A local coach #3 remains draft and unmerged.
• iPhone 12 Pro validation has not run.
• Batch B has not started.
• The next product gate remains a read-only recovery audit.

Merge policy

Keep this PR draft and unmerged until the PM issues a separate integration
decision.